royer R-121 - Understanding Proximity Effect; Proximity Effect for Richer Sound

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good, it’s probably right. If it doesn’t, move the microphone. It’s often more effective to

reposition the microphone than to start fiddling with knobs. Knob twisting can affect

headroom and phase coherency and add unwanted noise.

The following is a list of variables that also account for “sweet spot” effect

1. Frequency response variations due to proximity effect.

2. Frequency response variation due to treble losses as a result of absorption and

“narrowing” of the pattern at high frequencies,causing weakening of highs as the

microphone is moved away from the sound source.

3. Rise in treble response on-axis due to diffraction.

4. Loss of treble response off-axis due to phase-loss effect.

5. Variation in ratio of direct/reverberant sound.

6. Tendency of a microphone to favor the nearest sound source due to a combination of

these items, plus the influence of inverse square law.

Other Types of Microphones

For the same ratio of direct/reverberant sound, omni-directional microphones must be

closer to the sound source than cardioid or bi-directional microphones. Microphones

should generally face the sound source head-on or else treble losses due to phase loss will

result. The exception here is for large condenser microphones, which often give the

flattest response at an angle of about 10-20 degrees (off axis), where phase loss and

diffraction effect offset each other somewhat.

The Sound That Is “More Real than Real”

Ribbon microphones have long been renowned for “rich bass”. This effect is largely due

to the fact that ribbon microphones generally have excellent bass response to begin with,

and at the same time exhibit an effect known as “proximity effect” or “bass tip-up”.

As illustrated in the following graph, a typical bi-directional ribbon microphone will have

a flat frequency response at a distance of about six feet from the microphone but at

shorter distances the bass response becomes boosted; the effect becomes increasingly

pronounced as the distance between the microphone and the sound source is reduced.

This bass-boosting characteristic can become quite intense and, if

desired, can be corrected by equalization. However, for a multiple microphone setup, the

pronounced bass boosting (due to proximity effect) can be turned to an advantage. If an

instrument, such as a trumpet, is extremely close-miked and the bass is cut to restore flat

response, unwanted low-frequency sounds are cut back by upwards of 20dB compared to

an unequalized microphone with a flat response. This discrimination is independent of

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